A Study to Investigate Efficacy and Safety of KP-001 Compared With Placebo in Patients Aged ≥2 Years With Common VM, Common LM, or KTS/CLOVES Syndrome

This is a phase 3, double-blind, randomized, placebo-controlled, parallel group, adaptive, multicenter study planned to be conducted at multiple sites in North America, Canada, Taiwan and South Korea. The purpose of this study is to measure the efficacy and safety of KP-001 compared with placebo in patients aged ≥2 years with common VM, common LM, or KTS/CLOVES syndrome. An independent data monitoring committee (DMC) will be established to determine whether to discontinue or continue the study. It will also determine the redesign of the number of cases based on the result of the interim analysis. The study will comprise the following: * Screening Period: Up to 42 days prior to the first dose of study intervention. * Treatment Period 1: This is a double-blind period in which KP-001 100 mg (or lower dose depending on their body weight) or placebo will be administered to patients once daily after breakfast until Week 24. * Treatment Period 2: After 24 weeks of double blind treatment, all patients will switch to the KP-001 open label extension and treated up to Week 52. * Follow-up Visit: This visit will occur 30 days after the last dose of study intervention, and assessments will be performed per the SoA. * Discontinuation Visit: Patients who discontinue study intervention will be requested to continue participating in the study and assessments will be performed per the SoA. If the patients request to withdraw from the study, all tests and evaluations when possible will be performed at Discontinuation visit.

Inclusion Criteria: 1. Patients aged 2 years or older at the time of consent or assent. 2. Patients diagnosed with ISSVA classification of common VM, common (cystic) LM (including mixed type consisting mainly of either VM or LM), or KTS/CLOVES syndrome. 3. Patients who cannot be cured by resection, who are difficult to resect based on the assessment of the Investigator, or who are considered refractory to available treatment by the Investigator, or who have a contraindication to available treatment. 4. Patients with at least one target lesion at least 4 cm in the longest diameter. 5. Patients with at least one MRI-volumetric target lesion at screening that is determined to be evaluable by the central imaging evaluator. 6. Patients with symptomatic disease, defined as: ・ For patients ≥8 years old: Pain NRS of ≥1 and ≤8 score at the screening visit will be eligible only if their daily pain NRS recorded via ePRO from screening to Day 1 (Week 0) does not show a maximum absolute change of ≥6 points. If patients are taking analgesic medication, there must be no change in the type or dosage of analgesic during the screening period. If patients do not have qualifiable pain, then Fatigue or Bleeding/Oozing NRS of ≥1 and ≤8 score at the screening visit is required. Patients with ≥6 points absolute change in pain NRS are eligible if at least one of either Fatigue OR Bleeding/Oozing NRS is ≥1 and ≤8. * For patients ≥3 years old to \